SmokStak

Automotive Spray Paint

Harry Matthews

| September/October 2003

The following comes from a recent topic on SmokStak, which can be found on the Internet at: www.engineads.com/ smokstak.cgi. As ever, various individuals started, commented on and concluded the following bulletin board thread.

Can anyone tell me if automotive spray paint like Centauri has
any advantages over canned spray paint? Also, what is the best
brand of spray can paint to use for resistance to gas and heat?
I'm not set up for a spray gun, so I'll likely be using a
spray can for my Witte. -Chris

When I painted my Mogul I did not trust spray cans to be the
correct color. I got the DuPont number and had spray cans mixed for
me. It was expensive ($10 per can), but I feel it was worth it and
the color is perfect. It will get soft with gasoline, so I need to
coat it with clear. It went on great and looks great. - Al

I can tell you for certain that the cheap 98-cent Kelly Green
from Wal-Mart will shift towards blue when exposed to 300-plus
degrees F on steam lines. I use it anyway and just touch up the
problem areas yearly. I've also had implement enamel from the
local Farm & Fleet (IHC red) that actually peeled off in
strips. If you spray bomb, Rustoleum is pretty good, except that
you have to watch the second coat, it can and will react with the
previous coat to give you a 'crinkle' finish. - Allen

There's a trick to spraying Rustoleum - read the fine print
on the can. You cannot spray a new coat after one hour or before 48
hours. In other words, you have to get all of your coats sprayed
within one hour or wait two full days before spraying another coat.
If you do otherwise, you'll get the dreaded crinkles and then
you will have to start all over again. - Harry

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I noticed with Rustoleum that after maybe 10 years it peels off
- leaving the primer intact and in great shape for the next paint
job. You can brush paint Centauri, but don't do it if it's
over 60 degrees F because it dries too fast. I know they tell you
to paint when it's over 70 degrees, but I had good results
painting my 8 HP Mogul with it when it was 40 degrees in the barn.
The cold actually slowed down the drying so I could finish the job
before the brush set up. You need to wear a good mask when you use
the stuff; it's got some pretty unhealthy chemicals in it.

Probably the most important part of the paint job is the prep
work. Everything must be clean and oil free. Spend as much time on
it as you need to get it right and it will show in your finished
work, no matter what you paint with. I have had good results with
Demkote paint sold by Grainger's. Also, Krylon seems to be
pretty good. Rustoleum, by far, takes the longest to dry. Good luck
-Rob

If you want to use Centauri in hot weather (which we have a lot
of down here in southern Mississippi), use a high temperature
thinner. It lets the paint dry much more slowly and lets the brush
marks flow out before it dries. If it still dries too quickly, you
can add a retarder to it and slow it down even more. By brushing it
on, you can add the gloss hardener to it and make it gas and oil
proof. But if you're going to stay in this hobby, get a paint
gun and start practicing with it. I think you'll be much more
satisfied with the results. You will also have access to an endless
number of colors from DuPont, Sherwin Williams, Ditzler, etc. -
David

What we found out (and were also told by our automotive paint
suppliers) was that two-and three-part mix automotive paint is
harder on the surface and is much more resistive to UV (sunlight).
When we spray red on our field trucks (by can), it will start
fading in about four to six months. Automotive paint will stay
shiny for a very long time. It might make a difference for you if
you are leaving it out for long periods of time. - Darryl

Lowe's building supply house has a spray outfit that
includes a quart cup, 1/2 pint gun, air brush, hose and fittings
for about $60. It's decent equipment, but the key is to keep it
clean. - Chuck

I'm still going with automotive acrylics and hardener, but
it sure is getting expensive. - Larry

Centauri is great, but will lift if soaked with gasoline for any
length of time. Most any paint will do so except the three-part
urethanes. They are the best, but expensive and hazardous to use.
They are very forgiving when sprayed, build-up multiple coats
quickly and have a super gloss. NAPA sells Duplicolor acrylic
enamel in spray cans. The color selection isn't great, but it
is as good as Centauri and sells for about $4 a can.

I weather tested it on my mailbox, and it still looks great
after a year. Rustoleum faded in less than two months in the
weather. And Rustoleum doesn't dry fast enough to remain dust
and bug free. I used to get Centauri put in spray cans for $3.65 a
can plus the cost of the Centauri paint. You get about six cans to
the quart, plus a little left over. This is somewhat expensive, but
a good way to handle small projects.

For larger engines, bite the bullet and get an inexpensive HVLP
(high volume, low pressure) spray gun. Even the cheap ones are
great. I got the pressure cup-type and find it more convenient for
use around my messy shop. I have also found a spray, gloss shellac
coating to help in gasoline spill areas. It is not soluble in
petroleum solvents. Just don't spill any alcohol on it.
-Jeff

I have to agree with Jeff. I used PPG's version of Centauri
and the paint did peel when soaked with gasoline. I used it on an
Allis-Chalmers, and other than the area just below the fuel
sediment bowl I have been happy. The tractor still looks good other
than that area and has otherwise held up well. - Dave

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Did you add the gloss hardener to it? If not, gasoline will
soften it up. With a hardener it cures out very fast, and then has
properties much like urethane without the mess. After it sets
overnight it is pretty much bullet proof, even on sheet metal fuel
tanks. I have seen it wrinkle around gas tank necks, but that is
usually caused from the flux used in sweating on the neck and cap.
Generally speaking, gas does not bother it - if it did, it
wouldn't be worth much on a car, because every time you filled
your tank you would wash the paint off the quarter panel -
David

A few years ago, after a gasoline wrinkle showed up under the
weeping check valve on my Hercules, I called Dupont and asked them
about gasoline proof paint. They told me that they only had one
type of paint that would be considered gasoline proof, and that was
'Imron.' Imron, of course, is a three-part urethane. I
asked about Centauri and hardeners, but they said it would still
wrinkle if the gasoline was left to soak on the paint. PPG said
just about the same thing.

The key is 'soak.' A spill or two (or three) won't
bother most cured, quality paints. But an overnight soak will
discolor the paint and eventually lift it. Just watch those leaks.
Most good auto finishing supply houses will pack aerosol cans for
you, but some cans and spray tips are better than others. You want
the flat, fan spray tip, which is usually a blue colored tip. I
have mixed Imron and used it in a universal aerosol spray kit found
in most hardware stores. It worked very well as long as the job was
small. The propellant can starts to freeze up if you spray too
long. -Jeff

I have heard that when Imron hardens, it really hardens and
won't come off easily if you need to strip the item for some
reason in the future. I saw a tow truck at a body shop that was
painted with Imron a good number of years before, and when they
sandblasted it, there was still quite a bit of paint left on the
truck. - Bill

Any idea where store I can buy custom spray cans? Do they use
compressed air as the propellant or propane? I have spray guns and
the stuff to do gun painting, but those cans are so convenient for
little jobs. It would take me a week to cover everything in the
barn, plus disposing of the waste thinners. I think it would be
nice to match homemade spray bombs and good paint in the right
color. - Rob

I get mine put into spray cans at my local automotive paint
store. It's not cheap, usually $17 to $20 a can. They will make
any color in any brand they carry, and sometimes when I buy a quart
I have them put some of it in a spray can. That way I have a
perfect match for later use and it won't be dried up two years
later when I need it. - Allen

SmokStak is an engine conversation bulletin board with
over 50,000 messages on file and is part of the Old Engine series
of Web sites that started in 1995 as 'Harry's Old
Engine.' Harry Matthews is a retired electronic engineer and
gas engine collector from Oswego, N.Y., now residing in Sarasota,
Fla.

'What we found out (and were also told by our
automotive paint suppliers) was that two- and three-part mix
automotive paint is harder on the surface and is much more
resistive to UV (sunlight).'

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